Distributor Drive Pinion Position Question

[Bookwus]

Hiya All,

Anybody out there in IACland have an insight as to why a distributor drive pinion refuses to align itself perpendicular to the case seam in a Type 1 engine?

With the main pulley at TDC, I cannot get the notch in the DDP to sit at 90* from the case seam. I can get it close (both ways) but not on the money. It's like there's something outta place.

By the way, the engine runs fine and I've remarked my main pulley to reflect the timing being a bit off. I was just curious about this whole issue.

[Amskeptic]

Hiya All,

Anybody out there in IACland have an insight as to why a distributor drive pinion refuses to align itself perpendicular to the case seam in a Type 1 engine?

With the main pulley at TDC, I cannot get the notch in the DDP to sit at 90* from the case seam. I can get it close (both ways) but not on the money. It's like there's something outta place.

By the way, the engine runs fine and I've remarked my main pulley to reflect the timing being a bit off. I was just curious about this whole issue.

You do not "re-mark" the main pulley. It is utterly independent of the issue with the distributor! The main pulley tells YOU that the piston is at TDC or whatever number of degrees before/after the piston may be.

It is YOUR responsibility to make the spark go off at the correct degrees on the main pulley, and the distributor drive gear/position/ is just completely so what who cares? You can slap that distributor in four ways to next Tuesday and swap spark plug wires in dizzying combinations, and everything will work fine. . . but you cannot screw with the crankshaft pulley marks. You know that 009 distributors have drive lugs that are often 90* out of phase with the stock OEMs? You can either put the distributor in 90* off and shift the wires back 90* on the cap, or you can install the drive gear 90* off if you must have a vacuum can properly placed. The bottom line is that the instant the points open, a spark is on its way. That instant is determined by the breaker cam nudging the point rider. You adjust your timing by positioning the distributor body which moves the point asembly, in relation to wherever the breaker cam lobe ends up. If the drive lug is not exactly perpendicular to the case, who cares? Just figure out which way satisfies your vacuum can positioning.
Colin

[Bookwus]

Hiya Colin,

You do not "re-mark" the main pulley.

Why?

It is utterly independent of the issue with the distributor!

Yes, I realize that.

The main pulley tells YOU that the piston is at TDC or whatever number of degrees before/after the piston may be.

And the new marks on the pulley reflect that fact. True TDC is marked, false TDC is also marked and false 7.5* BTDC (my timing mark) is also marked. I just added on marks which allow me to time the engine with my gun.

What am I missing here?

[denjohn]

Bookwus......your comments beg the question .......how do you know that the piston is at TDC when you made your new marks?
I reckon that if you remove the #1 or #3 plug and stick a straw in there, you will find that it is higher on the original mark than on your new mark.

[Bookwus]

Hiya den,

I just finished putting this engine together. It's at TDC with the main pulley dent lined up with the case seam. But at that point the notch in the DDP is a little off.

[denjohn]

Bookwus
What Colin said is spot on.........reckon you should just trust that until you have compelling reason to do otherwise................it doesn't make any diff if your DDP is not where you think it should be.
The TDC mark wants to be at TDC.
Been there.......done that:
http://www.thesamba.com/vw/forum/viewto ... highlight=

[Amskeptic]

What am I missing here?

There is nothing false between the strobe flash and the crank pulley mark. Doesn't matter a whit what happened with the distributor drive gear. The crank pulley TDC mark is a relationship with the piston, not the distributor. The 7.5* idle mark, the 28* BTDC mark are all relationships with the piston. The distributor's relationship with the breaker cam lobe and points fires the spark whenever and the strobe light reads when it happened. This is inviolable.
Colin

[Bookwus]

Hiya Colin,

Oh, I get it.

Even though I realized there was a "disconnect" between the rotor position and the position of the crank/pistons, there also seemed to be a disconnect in my approach to this situation. I was thinking this through the distributor rather than through the crank/pulley. This clarified nicely when I started using the crank pulley point of view.

Okie dokie, I'll clean up the pulley.

[hambone]

My drive slot is slightly off from perpendicular.
(I have the same issue on my engine)
Just get it close as ya can and don't sweat it.